Cloud computing is a phrase used to describe a variety of computing concepts that involve a large number of computers connected through a real-time communication network such as the Internet, see for example Carroll et al in “Securing Virtual and Cloud Environments” (Cloud Computing and Services Science, Service Science: Research and Innovations in the Service Economy, Springer Science Business Media, 2012). It is very similar to the concept of utility computing. In science, cloud computing is a synonym for distributed computing over a network, and means the ability to run a program or application on many connected computers at the same time.
In common usage, the term “the cloud” is essentially a metaphor for the Internet, see for example http://www.netlingo.com/word/cloud-computing.php. Marketers have further popularized the phrase “in the cloud” to refer to software, platforms and infrastructure that are sold “as a service”, i.e. remotely through the Internet. Typically, the seller has actual energy-consuming servers which host products and services from a remote location, so end-users don't have to; they can simply log on to the network without installing anything. The major models of cloud computing service are known as software as a service, platform as a service, and infrastructure as a service. These cloud services may be offered in a public, private or hybrid network. Today, Google, Amazon, Oracle Cloud, Salesforce, Zoho and Microsoft Azure are some of the better known cloud vendors. Whilst cloud computing can be everything from applications to data centers a common theme is the pay-for-use basis.
The major cloud vendors provide their services through their own data centers whilst other third party providers access either these data centers or others distributed worldwide to store and distribute the data on the Internet as well as process this data. Considering just Internet data then with an estimated 100 billion plus web pages on over 100 million websites, data centers contain a lot of data. With almost two billion users accessing all these websites, including a growing amount of high bandwidth video, it's easy to understand but hard to comprehend how much data is being uploaded and downloaded every second on the Internet. At present the compound annual growth rate (CAGR) for global IP traffic between users is between 40% based upon Cisco's analysis (see http://www.cisco.com/en/US/solutions/collateral/ns341/ns525/ns537/ns705/ns827/white_paper_c11481360_ns827_Networking_Solutions_White_Paper. html) and 50% based upon the University of Minnesota's Minnesota Internet Traffic Studies (MINTS) analysis. By 2016 this user traffic is expected to exceed 100 exabytes per month, over 100,000,000 terabytes per month, or over 42,000 gigabytes per second. However, peak demand will be considerably higher with projections of over 600 million users streaming Internet high-definition video simultaneously at peak times.
All of this data will flow to and from users via data centers and accordingly between data centers and within data centers so that these IP traffic flows must be multiplied many times to establish total IP traffic flows. Data centers are filled with tall racks of electronics surrounded by cable racks where data is typically stored on big, fast hard drives. Servers are computers that take requests to retrieve, process, or send data and access it using fast switches to access the right hard drives. Routers connect the servers to the Internet. At the same time these data centers individually and together provide homogenous interconnected computing infrastructures. When hosted in massive data centers these are also known as warehouse scale computers (WSC) which provide ubiquitous interconnected platforms as a shared resource for many distributed services.
At the same time as requiring a cost-effective yet scalable way of interconnecting data centers and WSCs internally and to each other most datacenter and WSC applications are provided free of charge such that the operators of this infrastructure are faced not only with the challenge of meeting exponentially increasing demands for bandwidth without dramatically increasing the cost and power of their infrastructure. At the same time consumers' expectations of download/upload speeds and latency in accessing content provide additional pressure.
Accordingly data center interconnections, wherein we encompass WSCs as well as traditional data centers within the term data center, have become both a bottleneck and a cost/power issue. Fiber optic technologies already play critical roles in data center operations and will increasingly. The goal is to move data as fast as possible with the lowest latency with the lowest cost and the smallest space consumption on the server blade and throughout the network.
According to Facebook™, see for example Farrington et al in “Facebook's Data Center Network Architecture” (IEEE Optical Interconnects Conference, 2013 available at http://nathanfarrington.com/presentations/facebook-optics-oida13-slides.pptx), there can be as high as a 1000:1 ratio between intra-data center traffic to external traffic over the Internet based on a single simple request. Within data center's 90% of the traffic inside data centers is intra-cluster. Further, Farrington notes that whilst a Folded Clos topology provides the best economics at the largest scales the cabling complexity is a daunting problem as it is quadratic function of the number of nodes. Farrington notes that the issue of reducing the cabling complexity of Folded Clos topologies is an industry-wide problem worth solving.
Accordingly, it would be beneficial for new fiber optic interconnection architectures to address the traditional hierarchal time-division multiplexed (TDM) routing and interconnection and provide reduced latency, increased flexibility, lower cost, lower power consumption, and provide interconnections exploiting N×M×D Gbps photonic interconnects wherein N channels are provided each carrying M wavelength division signals at D Gbps.
Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.